Peptide and uses thereof

ABSTRACT

This present invention provides a novel peptide for inhibiting growth of microorganisms, a pharmaceutical composition, an antimicrobial composition comprising such novel peptide, and a method for inhibiting growth of microorganisms. The novel peptide for inhibiting growth of microorganisms has amino acid sequence: KX1LRX2X3X4RRWX5, wherein X1, X2, and X5 are selected from the group of W and R, respectively; X3 is selected from the group of V and P; and X4 is selected from the group of R and methylated W. The method for inhibiting growth of microorganisms disclosed in this present invention comprises administering the novel peptide, the pharmaceutical composition, or the antimicrobial composition.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to an artificial synthesis protein, speciallyrelates to a novel peptide and uses thereof.

2. Description of the Related Art

Many bacteria have drug resistance because of abuse of antibiotics inrecent years. For example, about more than half of Staphylococcus aureusfound in intravenous catheters are resistant to Penicillin. Drugresistant bacteria give anti-antibiotic genes to next generation throughplasmid, which causes that drug resistant bacteria can't be eliminatedeffectively. This situation leads to a serious problem when treatingrelated diseases caused by bacteria.

In order to avoid shortcomings of traditional antibiotics, manyresearches recently focus on developing the antimicrobial peptide toassist organism in resisting or eliminating foreign pathogens. To bemore specifically, the antimicrobial peptide has the followingadvantages over traditional antibiotics. First, the antimicrobialpeptide has broad and rapid antimicrobial activity and a smallereffective dosage which is unlikely to cause drug resistance ofmicrobacteria. Second, the antimicrobial peptide can stimulate immunecell of a organism to increase immunity of the organism againstdiseases.

Hence, there are few antimicrobial peptides used for drug preparation.For example, Magainin (Pexiganan) is applied for treating diabetic footulcers. Indolicidin (MBI-549) is applied for treating acne. Although theantimicrobial peptide have plenty of types and good antimicrobialactivity, however, when the conformation of a antimicrobial peptide islinear, the antimicrobial peptide may be hydrolyzed by enzymes and loseits activity in vivo. To make the antimicrobial peptide is lesssusceptible to enzyme hydrolysis in vivo, in further to increasestability of the antimicrobial peptide against enzymes. Recentdevelopment of the antimicrobial peptide mainly focus on cyclicpeptides. However, although the antimicrobial activity of theantimicrobial peptide is maintained in vivo by changing theconformation, it still needs to improve the safety of the antimicrobialpeptide for human body. For example, the antimicrobial peptide caneffectively and safely apply on human body only when the side effect,such as hemolysis, is controlled.

Accordingly, it is the most important challenge for researchers todevelop an antimicrobial peptide with good antimicrobial activity andhigh safety.

SUMMARY OF THE INVENTION

The major propose of this present invention is to provide a novelpeptide which can resist bacteria effectively and avoid producing drugresistant pathogens.

Further another purpose of this present invention is to provide a novelpeptide having low hemolysis which can reduce side effects and risks oforganisms.

Further another purpose of this present invention is to provide apharmaceutical composition which by administering an effective dosage ofthe peptide disclosed in this present invention to a subject to inhibitgrowth of microorganisms for treating diseases caused by microorganismsand with good safety to human.

Further another purpose of this present invention is to provide anantimicrobial composition which can effectively inhibit growth ofmicroorganisms to prevent the harm caused by microorganisms toorganisms.

In order to achieve these foresaid purposes, a preferable embodiment ofthis present invention discloses a novel peptide comprising thefollowing amino acid sequence: KX₁LRX₂X₃X₄RRWX₅, wherein X₁, X₂, and X₅are selected from the group consisting of W and R, respectively; X₃ isselected from the group consisting of V and P; and X₄ is selected fromthe group consisting of R and methylated W.

The novel peptide disclosed by this present invention has effect ofinhibiting growth of microorganisms and low hemolysis. Hence, the novelpeptide disclosed by this present invention can be administrated to asubject safely.

In another preferable embodiment of this present invention, the aminoacid sequence of the novel peptide is SEQ ID NO. 1 in which has theseventh amino acid methylated.

In another preferable embodiment of this present invention, the aminoacid sequence of the novel peptide is SEQ ID NO. 2.

In another preferable embodiment of this present invention, the aminoacid sequence of the novel peptide is SEQ ID NO. 3.

In the embodiments of this present invention, the novel peptide can beproduced by other methods known by person skilled in the art of thispresent invention and having general knowledge. For example, thesemethods comprise artificial synthetic technique, platform forrecombinant protein expression, etc. Preferably, the novel antimicrobialpeptide of present invention can be synthetized by solid phase peptidesynthesis.

Another embodiment of this present invention discloses a pharmaceuticalcomposition which comprises an effective dosage of the novel peptidedisclosed in this present invention and at least a pharmaceuticalacceptable carrier. By administering the pharmaceutical composition to asubject, growth of microorganisms in the subject can be inhibited andhence the disease caused by the microorganisms is cured. In addition,because of the low hemolysis of the novel peptide disclosed in thispresent invention, when administering to the subject, the novelpharmaceutical composition will not induce hemolysis. Therefore, it canprevent or reduce dramatically the side effects induced by traditionalantimicrobial pharmaceutical composition.

Generally speaking, the microorganisms are pathogens comprising but notlimited to Escherichia coli, Staphylococcus aureus, or Pseudomonasaeruginosa.

In one embodiment of this present invention, the antimicrobialcomposition at least comprises an effective dosage of any one of theantibacterial peptides mentioned above.

The antimicrobial composition can be produced as different forms dependson needs. The forms comprise but not limited to spray, liquid, solid,and jelly etc. In addition, the antimicrobial composition can be usedexternally, internally, and used as environmental product with differentformulations.

By using the antimicrobial composition, growth of the microorganisms canbe effectively controlled to prevent inflammation on a organism causedby microorganisms or to prevent destruction of environment or goods. Themicroorganisms are pathogens comprising but not limited to Escherichiacoli, Staphylococcus aureus, or Pseudomonas aeruginosa.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the growth curve of Escherichia coli:

FIG. 2 is the growth curve of Staphylococcus aureus.

FIG. 3 is the growth curve of Pseudomonas aeruginosa.

DETAILED DESCRIPTION OF THE INVENTION

The meaning of the technological and scientific terms disclosed in thespecification and claims of this present invention is the same as theunderstanding from a person skilled in the art of this present inventionand having general knowledge. The content of this present invention isthe first priority of explanation if there are contraries.

The “artificial synthesis technique” is a common technique known by anordinary person skilled in the art of this present invention. Theartificial synthesis technique artificially chains amino acids insequence to produce a polypeptide, wherein the artificial synthesistechnique comprises chemical synthesis method and a peptide synthesizer.Usually the artificial synthesis technique has the following advantages:conveniently changing the primary structure of a polypeptide during theprocess of artificial synthesis, adding special amino acids, andmodifying the end of polypeptide. Generally speaking, the artificialsynthesis technique is classified as solid phase peptide synthesis andliquid phase peptide synthesis. The liquid phase peptide synthesis hasto extract intermediate product after each time of amino acid chainreaction. As the intermediate product of each extraction is usuallymixtures, chromatographic purification is needed to purify the mixtures.Hence, synthesis of the polypeptide by liquid phase peptide synthesishas to involve many complicated extractions and purifications to obtainhigh plurality product. The solid phase peptide synthesis performs aminoacid chain reactions on solid polymeric particles (or polymericsupports) in solvent. During the process of solid phase peptidesynthesis, first of the amino acid of a target polypeptide as theN-terminal end is covalently attached to a solid polymeric particle,then the following amino acids are linked to the first amino acid byspecific covalent bonds, and finally the peptide is synthesized. Due tothe fact that the polymeric particle is insoluble in the solvent, so thesolid polymeric particles and the peptide attaching on the solidpolymeric particles can be separated from the solvent and side productsby washing and filtering at the end of synthesis. As purifications arenot required, the solid phase peptide synthesis not only has higheryield but also significantly shorten reaction time and is superior inlong chain polypeptide synthesis. Therefore, the solid phase peptidesynthesis is commonly used in peptide synthesis.

The “platform of recombinant protein expression” means construction of anucleic acid sequence which expresses a specific protein on anexpression vector through biotechnology. The recombinant expressionvector is then transformed into a host cell such as Escherichia coli,yeast bacteria, lactic acid bacteria, etc. to obtain the specificprotein by expression the nucleic acid sequence in the host cell.

The “effective dosage” means the amount of compound or active ingredientto generate specific effect. It can be shown as the weight percentage ina composition. It can be understood by the person skilled in the art ofthis present invention and having general knowledge that the effectivedosage will be different because of the administering pathway which istrying to induce specific effect. Generally speaking, the amount of theactive ingredient or compound in the composition can take about 1% toabout 100% of weight, the better one will be about 30% to about 100% ofweight.

The “pharmaceutical composition” includes an effective dosage ofcompound or active ingredient which is necessary to produce specificeffect, and at least a pharmaceutical acceptable carrier. It can beunderstood by the person skilled in the art of this present inventionand having general knowledge that the type of composition can bedifferent according to the administering pathway such as tablet, powder,injection, etc. The carrier also can be solid, semisolid or liquidaccording to the type of the composition. For example, the carriercomprises but not limited to gelatin, emulsifiers, hydrocarbon mixtures,water, glycerin, physiological saline, buffered physiological saline,lanolin, paraffin wax, beeswax, dimethicone or ethanol.

The “pharmaceutical acceptable carrier” is compatible with the activeingredient of a pharmaceutical composition. Preferably, thepharmaceutical acceptable carrier can increase the stability of thepharmaceutical composition and with no harm to a subject. According tothe type of the pharmaceutical composition, the pharmaceuticalacceptable carrier comprises but not limited to corn starch, lactose,cellulose, magnesium stearate, colloidal silicon oxide, maltodextrin,water, etc.

The “a/an” or “the” in the specification and the claims of presentinvention means one and more than one unless otherwise stated.

Hereinafter, there are several examples for further illustrating theeffect of this present invention. But these examples are only forexplanation. Any words mentioned do not tend to limit the scope andmeaning of the specification and claims of this present invention.

Example 1: Solid Phase Peptide Synthesis

In the example 1, the Fmoc solid phase peptide synthesis was used tosynthesize the target peptide.

First, the amount of the amino acid, HOBT (Scientific), HBTU (AgeneMax), DIEA (SIGMA), the resin support (PAL Rink resin, NOVA Biochem, SanDiego, Calif., USA) needed during the synthesis were calculated. Afilter and the resin support was sequentially placed into a PD-10 column(17-0435-01, Amersham Biosciences) and then 5 mL dichloromethane (DCM)was added into the PD-10 column to expand the resin supports. The liquidin the PD-10 column was then drawn out and waited 5 minutes forreaction. The above mentioned steps were repeated 2 times. 5 mLdimethylformamide (DMF) was then added into the PD-10 column to keep theresin support moisture. The remaining DCM was washed, waited 5 minutesfor reaction, and the liquid in the PD-10 column was then removed.

Next, synthesis was proceeded. 5 mL, 20-30% (v/v) piperidine was addedinto the PD-10 column to remove the No.-Fmoc protection group of theresin support. After 15 minutes reaction, the liquid in the PD-10 columnwas removed. The amino acid with No.-Fmoc protection group, HOBT, HBTU,DIEA and 5 mL DMF were mixed for 1 minute to activate the C-terminal ofthe amino acid. The mixture was added into the PD-10 column to proceedamino acid coupling reaction for 2 hours to attach the amino acids andthe Knorr resin. After that, the liquid in the PD-10 column was removed.5 mL DMF was added into the PD-10 column to wash unreacted amino acidsand reagent, and then removed the liquid in the PD-10 column. The abovementioned synthesis procedures were repeated to attach amino acids tothe resin support in sequence.

During the process of synthesis, Ninhydrin test was used to test whetherthe coupling is successful. The procedures of Ninhydrin test lists asfollows: 10 μL Ninhydrin test reagent was placed into a test tube and afew resin supports were placed into the test tube as well. The test tubewas heated by an oil bath of 95° C. for 5 minutes. The couplingsucceeded if these resin supports became transparent or yellow. Afterthat, these resin supports attached next amino acid after DMF washing.The coupling failed if these resin supports became dark blue and onemore repeated coupling was needed.

After the synthesis terminated, 5 mL, 20-30% (v/v) piperidine was addedinto the PD-10 column in sequence for 15 minutes to remove the No.-Fmocprotection group of the peptide and then to the side chain protectiongroup of the peptide. The target peptide detached from the resin supportvia chemical cleavage. Crude product of the linear peptide was obtainedafter vacuum filtration of the target peptide and drying the filtrate.

Example 2: Synthesizing Methylated Peptide

First, peptide was synthesized by solid phase peptide synthesis andattached on resin support. Next, o-NBS-Cl (4 eq) and collidine (10 eq)were added into 2 mL N-Methyl-2-Pyrrolidone (NMP), which is theprotection agent of N-terminal and catalyst reagent. After reacting for15 minutes, the resin support was washed by NMP for 5 times to obtainamino acids with N-terminal having o-NBS protection group. After that,catalyst DBU (3 eq) was mixed with 1 mL NMP for pre-activation. Then,dimethyl sulfate (10 eq) and 1 mL NMP, which is a methylation reagent,were added to proceed methylation reaction with the amino acid withN-terminal having o-NBS protection group to obtainNa-Methyl-Na-o-NBS-peptides. Then, a deprotection reagent was preparedby mixing DBU (5 eq), 2-mercaptoethanol (10 eq), and 2 mLN-Methylpyrrolidine. The deprotection reagent was added into thereaction column for 1 hour and repeated 2 times to remove o-NBSprotection group to obtain N-methylated peptides. Then, amino acidcoupling reaction was proceeded by solving the next amino acid (3 eq),HATU (3 eq), HOAt (3 eq) and DIEA (6 eq) in 4 mL NMP as a couplingreagent. Repeated the above mentioned steps until all the amino acid wasattached on the resin support. Finally, the side chain protection groupwas removed and cleavage of the peptide from the resin support by TFA asa cleavage reagent for hours shaking. Crude product of the methylatedpeptide was obtained by filtering and purifying the filtration.

Example 3: Purifying Peptide

A semi-preparative column on a reverse phase-high performance liquidchromatography (RP-HPLC) was used to confirm the plurality and retentiontime of crude product of the peptide and proceeding purificationthereof. Wherein the column was 5 μm C₁₈ column and the flow rate of themobile phase was 4 mL per minute. The composition of the mobile phasewas solvent A for 4 L distilled deionized water (0.22 μm filtermembrane) and 2 mL, 0.05% trifluoroacetate, and solvent B for 4 Lacetonitrile and 2 ml, 0.05% trifluoroacetate. The detection wavelengthwas 225 nm. And finally, the purified product was frozen dried to obtainpeptide powder.

Example 4: Identifying Molecular Weight of the Peptide

The molecular weight of the synthesized peptide was identified bymatrix-assisted laser desorption/ionization time-of-flight massspectrometry (MALDI-TOF).

The sample and the matrix solution (CHCA) having absorption in laserenergy were mixed evenly with a mixing ratio of 1:1. 1 μL of theforesaid mixture was placed on the sample tray and waited until thevolatile solvent evaporated. The matrix and the sample became a solidcocrystal on the sample tray and the cocrystal was then send into theion source of MALDI-TOF to receive pulsed laser irradiation fordesorption in vacuum. After that, the m/z ratio was measured by the massanalyzer to evaluate the molecular weight.

Example 5: Preparing Peptide

Prepared peptides listed in Table 1 by the methods described in example1 to 4, wherein “Me” means the amino acid after “Me” has beenmethylated.

TABLE 1 Synthesized peptides and amino acid sequence thereofSEQ ID No of amino acid peptide sequence amino acid sequence Peptide 1SEQ ID No. 1, wherein the 7^(th) KWLRRVMeWRWWR amino acid is methylatedPeptide 2 SEQ ID No. 2 KWLRRPWRRWR Peptide 3 SEQ ID No. 3 KWLRWVRRRWWPeptide 4 SEQ ID No. 4, wherein the 7^(th) KRLRRVMeWRWWRamino acid is methylated Peptide 5 SEQ ID No. 1, wherein the 5^(th)KWLRMeRVWRWWR amino acid is methylated Peptide 6 SEQ ID No. 1KWLRRVWRWWR

Example 6: Microbiological Culture

Three bacteria strains, Escherichia coil (ATCC 25922), Staphylococcusaureus (ATCC25923), and Pseudomon asaeruginosa (ATCC27853) were broughtfrom the Food Industry Research and Development Institute, Hsinchu,Taiwan.

Each of the strain (0.1-0.2 mL) was inoculated on an agar gel medium(Merck, Whitehouse, Station, N.J., USA) and isolated into single colonyby streak plate method. Each of the strain was spread evenly by asterile L-shaped glass rod and incubated overnight. After that, thesingle colony on each agar gel medium was transferred to liquid LBmedium (Merck, Whitehouse, Station, N.J., USA) and incubated at 37° C.in an incubator.

After overnight incubation, the broth containing each of the strains wasdiluted with sterile water in different ratio. The dilution ratio of thebroth and sterile water are 1:2, 1:4, 1:8, 1:16, 1:32, and 1:64. Opticaldensity of each diluted broth was measured at 595 nm (OD₅₉₅) by a UVspectrometer to evaluate the number of bacteria in the broth and to plotthe standard growth curve.

The growth curve of Escherichia colt, Staphylococcus aureus, andPseudomonas aeruginosa was obtained respectively by the above mentionedsteps and shown in FIG. 1 to FIG. 3.

Example 7: Antimicrobial Test

Each bacteria strain from example 6 was incubated to its mid-log phaseat 37° C. in 2 mL Lysogeny broth (LB) in an incubator, wherein themid-log phase of Escherichia coil is 4 hours, the mid-log phase ofStaphylococcus aureus is 6 hours, and the mid-log phase of Pseudomonasaeruginosa is 8 hours. According to 0.5 McFarland Standard, the numberof bacteria in a broth is 1×10⁸ CFU/mL when the OD₅₉₅ is 0.08-0.09.Hence, each of the bacterial broth was diluted with sterile water tohave the same OD₅₉₅ of 0.5 McFarland Standard. And then, the number ofbacteria in each broth was diluted from 1×10⁸ CFU/mL to 1×10⁵ CFU/mL.Finally, each broth has bacterial number of 5×10⁵ CFU/mL in MuellerHinton broth (MHB).

199 μL of each of the foresaid diluted broth was respectively placedinto a 96 well plate, and 1 μL of each peptide from example 5 was addedinto each well to incubate at 37° C. in an incubator for 16 hours. TheOD₅₉₅ of the coculture of each broth and each peptide was measured by amicroplate spectrophotometer. In addition, the bacterial broth withoutthe peptide served as positive control (PC), and the free broth MHBculture medium served as negative control (NC). The minimum inhibitoryconcentration (MIC90) of each peptide against each bacteria was measuredaccording to the following equation, wherein A is the absorbance. TheMIC90 results are listed in Table 2.MIC90≤[(A _(peptide) −A _(NC))/(A _(PC) −A _(NC))]

In addition, to measure the minimum bactericidal concentration (MBC), 1μL of each broth cocultured with the peptide was sprayed on a flat platemedium at 37° C. in an incubator for 24 hours. If the incubation resulthas no bacteria, the concentration of the reagent is MBC. The MBCresults are listed in Table 3.

TABLE 2 Minimum inhibitory concentration (MIC90) of each peptide againstbacteria Minimum inhibitory concentration (MIC90) (μM) StaphylococcusPseudomonas Escherichia coli aureus aeruginosa peptide 1 5 5 10 peptide2 2.5 2.5 5 peptide 3 2.5 2.5 5 peptide 4 20 10 20 peptide 6 5 5 5

TABLE 3 Minimum bactericidal concentration (MBC) of each peptide againstbacteria Minimum bactericidal concentration (MBC99.9) (μM)Staphylococcus Pseudomonas Escherichia coli aureus aeruginosa peptide 120 40 10 peptide 2 10 5 20 peptide 3 10 5 20 peptide 4 20 10 20 peptide6 5 10 5

From the results of Table 2 and Table 3, it can be understood that SEQID No. 1 which the 7^(th) amino acid is methylated, SEQ ID No. 2 and 3have effect of inhibiting growth of microorganisms.

Example 8: Hemolysis Assay

1-3 mL human blood was centrifuged at 3000 rpm, 4° C. for 10 minutes.The supernatant was discarded. The remaining was washed with coldphosphate buffer saline (PBS) and centrifuged at 3000 rpm, 4° C. for 1minute. The supernatant was discarded. The remaining red blood cellswere washed and diluted as 2% red blood cell solution with cold PBS.

A mixture of 100 μL red blood cell solution and 100 μL PBS was served asa negative control. A mixture of 100 μL red blood cells solution and 100μL 0.2% Triton X-100 was served as a positive control. The solution ofpeptide 1, peptide 2, peptide 3, peptide 5, and peptide 6 wererespectively mixed with red blood cell solution with the same volume andincubated at 37° C. for 1 hour. After incubation, the mixture wascentrifuged at 3000 rpm, 4° C. for 10 minutes. Each of the supernatantwas collected to measure the absorbance at wavelength of 405 nm by anELISA plate reader. The hemolysis of each peptide was calculatedaccording to the following equation, wherein Abs represents theabsorbance. The hemolysis results are listed in Table 4.[(Abs_(peptide)−Abs_(PBS))/(Abs_(Triton X-100)−Abs_(PBS))]×100

TABLE 3 Hemolysis of each peptide Hemolysis (%) peptide 1 20.1 peptide 23.4 peptide 3 3.4 peptide 5 44.9 peptide 6 70.7 Negative control 0Positive control 100

From the results of Table 4, it can be understood that hemolysis of thepeptide 1-3 were obviously lower than that of the peptide 5 and 6,wherein the peptide 2 and 3 were the lowest. As known by the personskilled in the art of this present invention and having generalknowledge, high hemolysis breakdowns red blood cells of a subject andinduces side effects such as anemia, pain, etc. It can even induce muchmore serious side effects which endanger life. In other words, becauseof lower hemolysis, administering the peptide 1-3 to a subject can lowerrisk to induce hemolysis, which means to induce minor side effects ofthe subject.

In addition, although there are methylation in amino acid sequence ofthe peptide 1 and 5, but according to different methylation position,the hemolysis of the peptide 1 is significantly lower than the peptide5. It can be understood that not every methylated peptide cansignificantly avoid hemolysis.

Furthermore, it can be understood from the results of Table 2 to 4 thateven the peptide 6 has antimicrobial activity, but the hemolysis ofpeptide is higher than the peptide 1, peptide 2, and peptide 3. Asubject will face an elevated risk of hemolysis if the peptide 6 isadministered. Therefore, the peptide having high hemolysis cannot becomeor apply as a pharmaceutical composition or an antimicrobialcomposition.

From the results of foresaid examples, it can be understood that thenovel peptide disclosed in present invention has great antimicrobialactivity and low hemolysis, and thus to become effective ingredient of apharmaceutical composition or an antimicrobial composition which can beadministered to a subject safely.

From the results of foresaid examples, it can be understood that thenovel peptide disclosed in present invention has following advantages:

First, the novel peptide disclosed in this present invention hasantimicrobial activity to inhibit variable pathogens. Hence, the peptidecan become the effective ingredient of a pharmaceutical composition oran antimicrobial composition which having antimicrobial activity indaily life or clinically.

Second, the novel peptide disclosed in this present invention can reducemuch more side effects of a subject and have higher safety while havingantimicrobial activity.

Third, the novel peptide disclosed in this present invention can preventto induce drug resistance of pathogens, which much more improve thelacks of traditional antibiotics.

The above-mentioned detailed description and specific examples are givenfor illustration of this present invention only. Any easy changes ormodifications base on examples in the description by the person skilledin the art of this present invention will be included within the scopeof following claims.

What is claimed is:
 1. A synthetic peptide comprising the amino acidsequence: SEQ ID NO.2.
 2. The peptide of claim 1, wherein the peptide isproduced by solid phase peptide synthesis.
 3. A pharmaceuticalcomposition comprising an effective dosage of the peptide of claim 1 anda pharmaceutical acceptable carrier.
 4. An antimicrobial compositioncomprising the peptide of claim 1.